Hi Roberto,
Thanks for trying that.
Can you check that your translation files have been updated? Please keep in mind that with each release, we add, edit or remove strings in the plugin, and as a result, those things are changed in the translation file. If you are using a translation file, you should update your translation files with EACH upgrade of the plugin.
Follow the instructions in this article for the steps to take to upgrade your translation file: http://businessdirectoryplugin.....tion-file/
If that doesn't help, please let me know the exact strings you tried to translate. You may want to use screenshots as well as text to give me an idea of what you tried here. Please let me know.